Semiconductor bandgap voltage reference (BVR) circuits are used as voltage references for operating voltages in analog, digital, and mixed analog-digital circuits. For example, an accurate voltage reference is needed in almost any system on chip (SoC). Conventional BVR circuits operate on the principle of the addition of two partial voltages with opposite temperature responses. While one partial voltage rises proportionately with the absolute temperature (PTAT partial voltage, also referred to as “proportional to absolute temperature”), the other partial voltage falls as the temperature rises (CTAT partial voltage, also referred to as “complementary to absolute temperature”). An output voltage with low sensitivity to temperature is obtained as the sum of these two partial voltages.
With the development of ever-smaller microprocessors and memory cells, such as microprocessors and memory cells based on multiple gate field-effect transistors (MuGFET) and further process scaling, bipolar devices (e.g., bipolar junction transistor (BJT)) used in conventional BVR circuits have shown drastic degradation in reliability, particularly when the current-gain (β) of a BJT is low, e.g., less than three.